How can I use the "Fill" in texture paint on only a single face instead of the entire uv map?
select your object

choose texture paint from the menu

tab -&gt; edit mode

choose &quot;face select mode&quot;




select the faces you want to paint on

tab -&gt; texture paint mode

click this button: paint mask




paint what you want -&gt; now you just paint on that faces you selected

you can select the faces in the texture paint view too...just tap on select and choose your favorite selection mode



you can check a tutorial video here:
https://youtu.be/TYq49SLlot8.  (just be a little bit patient, my internet is not fast)